I apologize for not being able to say Where I found mine. Thanks to flying, I was able to find this guy and finally capture him after killing the previous 3 I ecncountered ny misjudging the damage when attacking. I finally just used my Anubisath to poke hime down and then 6(?) trap throws.

It's a timing thing. I ran around for hours killing Thornclaw Broodlings (once I'd captured both breeds of course) and I could not make the Vicious appear. So I logged out for the night. Next day I found three of them within 10 minutes of logging in - all rare, (I think that's the only kind). I captured just one of them since there is only one breed.

Clearly when it's time for them to spawn, they spawn, and no amount of running around nuking Thornclaws is going to help.

If the pet has spawned but you need to clear trash to get to it, please please please be mindful of any items or trinkets you have equipped that do aoe damage. After killing critters for over an hour one finally spawned between two mobs and my trinket kindly dropped a meteor on the pet, killing it instantly.

I did manage to get another to spawn about 20mins later in the same spot, which I basically stripped down naked to capture!

25:63(ish), just outside a little cave. Natural rare P/B! I was thrilled. Hard fight, too - backed up by a Sandpiper and a Violet Firefly. The spider alone had nearly taken out my Molten Corgi and Feline Familiar. Thank goodness for my Sentinel's Companion and the two backline opponents being Flying.

Also confirming Starlyte post, but I found mine North West of the F in Felsoul Hold (got rare too :D). Got aggro on winning the fight but not the Wandering Felsoul Crusher (elite giant 15M+health) So watch out where you start the fight.

After spending about two hours, roaming around the Felsoul Hold, I finally found the last pet I needed for the Safari achievement. My rare, blue Vicious Broodling was just standing there, waiting for me at 28.43 73.08.

The Thornclaw broodling is a placeholder for these guys. I spent about 5 hours hunting this lil guy. So kill any thornclaw broodling to force this guy to pop and capture. The first one I saw I accidently killed took another 2 hours to see another one pop in completely different area. There are several spawn points for the Thornclaw Broodling. There is a Nice place to also farm the Eye of Inquistion and has 3-5 Thornclaw Broodling spawn points. Happy Hunting!

While the warning is that 'players must be level 110 to enter Suramar', I was able to come here at level 100. Mind you, all the enemies are level 110 (other than a few scaling rares) so expect to get your butt handed to you. However, if you're an obsessive collector the way I am, you can come and get these early.

Just be aware that you're essentially walking into an area completely filled with level 110 demons, including several elites. Being level 110 is probably the safest way to do it.